A fiber sensing technology is a novel sensing technology developed in recent several decades, which uses an optical wave as a sensing signal and uses a fiber as a transmission carrier to sense and detect external monitored signals, and has the advantages on the aspects of sensing manner, sensing principle, signal detection and processing that the traditional electric sensor does not have. Compared with a traditional sensing component, the fiber sensing technology has the advantages of good anti-electromagnetic interference, chemical resistance, and radio resistance performances; moreover, the fiber sensing technology has no electric charge, is small in volume, is light in mass, and is easy to bend, etc.
When the sensing fiber is affected by environmental factors like external strain and temperature, the optical wave transmitted in the fiber is easy to be modulated by these external fields or factors, so as to result in changes on optical wave characterization parameters, such as the changes of light intensity, phase position, frequency, polarization state, etc. The information of an external monitored factor may be obtained through monitoring the changes of the information, which brings a big trouble to the monitoring of the sensing fiber. If the factors causing the interference and effects outside cannot be determined through the changes of the optical wave characterization parameters, then the environmental factors cannot be singly analyzed preferably, and the proportion of each affecting factor cannot be recognized as well, so that targeted evaluation cannot be preferably conducted. Therefore, it is necessary to establish an instrument for filtering some external factors in advance.
The most common factor is the mutual interference influence between the strain and the temperature, and it only needs to consider the single strain condition under multiple conditions, but the temperature effect is extremely obvious in actual condition. Multiple temperature interference-free or temperature compensation measures are very inaccurate at present, and there is no relatively reasonable scheme; and in addition, the method is too simple. Therefore, it is very important to develop a temperature interference-free sensing fiber monitoring apparatus.
When the stress-strain numerical value of a structure is merely obtained under an actual working environment, it is difficult to avoid the effects of temperature inside and outside the structure. Regarding to the structure to be monitored, the interference of multiple complicated factors outside causes that the structure to be monitored represents multiple complicated external information, and the external information is the fusion body of the internal information of the structure to be monitored. According to the external information extracted, even through multiple advanced data optimization algorithms are used, it is relatively difficult to accurately separate and recognize the information that is concealed in the structure to reflect the structure, which needs to start from a monitoring apparatus to develop a monitoring instrument that may eliminate some disturbing factors.